PMP Project Management Professional Study Guide, Third Edition (Certification Press)

Projects cannot last forever-thankfully. To effectively finish and manage a project, a project manager must be able to effectively manage time. Within a project there can be many factors that affect the project length: activity duration, project calendars, resource calendars, vendors, activity sequencing, and more. Time management begins with the constraints of the product schedule, the project calendar, the resource calendars, as well as the activities and their expected duration.

Many projects can rely on project templates that have worked before. Other projects, new and never-attempted technology, require that a project schedule be created from scratch. The WBS contributes to the activity list, which in turn, allows the project manager and the project team to begin activity sequencing.

Activities to be sequences must be estimated. The project manager and the project team must evaluate the required time to complete the work packages. The project manager can rely on a number of estimating methods to come to a predicted duration for activities. For example, a project manager may use analogous estimation of historical data to provide the needed estimate. Or, the project manager may use a parametric model to predict the amount of time for the activities. The importance of estimating is that each work package is considered and its duration calculated.

Within the process of activity sequencing there will be hard logic and soft logic. Hard logic is the mandatory relationships between activities: the foundation must be in place before the house framing can begin. Soft logic allows the relationship and order of activities to be determined based on conditions, preferences, or other factors. For example, the landscaping will happen before the house is painted so that dirt and dust won't get onto the fresh paint.

The relationships of activities are illustrated within a network diagram. Network diagrams show the path from start to completion and identify which activities are on the critical path. Of course, the critical path is the path with the longest duration and typically has zero slack or float. Activities on the noncritical paths may be delayed to the extent that they do not delay activities on the critical path.

Finally, project team members may have a tendency to bloat their duration estimates. Bloating the work to allow for 'wiggle room' on assignments can cause durations to swell way beyond the practical completion of the project. In lieu of bloated estimates, project team members and the project manager should use a percentage of the project time as management reserve. When activities are late, the tardiness of the work is borrowed from management reserve rather than tacked onto the conclusion of the project.